WASHINGTON — President Trump plans to recognize Jerusalem as Israel’s capital but not to move the American Embassy there for now, people briefed on the deliberations said on Friday, a halfway gesture intended to fulfill a campaign pledge while not derailing his peace initiative.

Mr. Trump is expected to announce the decision in a speech next Wednesday, these people said, though they cautioned that the president had not yet formally signed off on it and that the details of the plan could shift.

Those details, experts warned, are fiendishly complicated. The diplomatic status of Jerusalem is one of the world’s most contested issues, with Israel and the Palestinians claiming it as their capital. Its holy sites are sacred to Jews, Christians and Muslims, and any change in its status would have vast repercussions across the Middle East and other Islamic-majority countries worldwide.

Mr. Trump promised to move the American Embassy to Jerusalem from Tel Aviv as one of his first acts as president — a pledge that was popular with his evangelical supporters as well as with powerful Jewish donors, like the casino mogul Sheldon Adelson.

American presidents must sign a national security waiver every six months to keep the embassy in Tel Aviv. In June, Mr. Trump deferred a decision to move it to Jerusalem, under pressure from Arab leaders, who warned that it would ignite protests, and from advisers, including his son-in-law, Jared Kushner, who worried that it could strangle the administration’s attempt to foster peace in the generations-long dispute.

With another deadline looming next Monday, Mr. Trump is expected to sign an order keeping the embassy in Tel Aviv. But he will couple that with a statement that the United States recognizes Jerusalem as the capital — something that no president, Republican or Democrat, has done since the state of Israel was established in 1948.

Given the extreme sensitivities surrounding Jerusalem, Middle East experts said Mr. Trump’s plan was fraught with risk. Even after extensive consultations with Arab leaders, which the White House has not done, such a move could provoke volatile reactions.

“The devil is in the details of what they announce,” said Martin S. Indyk, who served as American ambassador to Israel under President Bill Clinton. “If this is not framed properly, far from resolving this issue, it will land the administration in even hotter water.”

Among the questions, Mr. Indyk said, are whether Mr. Trump will restrict recognition to West Jerusalem, whether he will mention Palestinian claims to East Jerusalem and how he will deal with Jerusalem’s status as a holy city — a factor that could determine whether Saudi Arabia supports or abandons his peace project.

News of Mr. Trump’s decision came amid fresh disclosures about how, even before he took office, he worked closely with Prime Minister Benjamin Netanyahu to scuttle a United Nations Security Council resolution critical of Israel’s settlement policy — subverting then-President Barack Obama, who had decided to allow a vote to go ahead.

Documents filed in connection with the guilty plea of Michael T. Flynn, Mr. Trump’s former national security adviser, revealed that on Dec. 22, 2016, a “very senior member” of Mr. Trump’s transition team instructed Mr. Flynn to contact foreign officials, including from Russia, “to influence those governments to delay the vote or defeat the resolution.”

Lawyers identified the senior transition official as Mr. Kushner. Russia rebuffed Mr. Flynn’s request and voted for the resolution, which passed after the United States abstained.

Mr. Trump has kept up his close relations with Mr. Netanyahu, though that may be tested if, as expected, the White House tries to jump-start peace negotiations between Israel and the Palestinians early next year.

While Mr. Netanyahu supports the decision to move the American Embassy, Israeli officials have not pushed the issue in recent months. Other leaders in the region, like King Abdullah II of Jordan, remain deeply opposed to it.

But Mr. Trump was under immense pressure from pro-Israel and evangelical supporters and is likely to repeat past assertions that it is not a matter of if, but when, the embassy will be moved to Jerusalem. He is also being pressed to declare that next week’s waiver will be his last — effectively promising to devise a plan by mid-2018 to begin relocating the embassy.

Declaring Jerusalem to be Israel’s capital would not itself mark a change in American law. In 1995, Mr. Clinton signed a statute declaring, “Since 1950, the city of Jerusalem has been the capital of the State of Israel.” But administrations have been allowed to decide, as a matter of policy, whether to recognize it as the capital, and none have done so.

That law requires the embassy to be moved to Jerusalem, unless the president issues a waiver finding that doing so would be against national security interests of the United States. American presidents have done so every six months since then to avoid prejudging the outcome of — and therefore hampering — an eventual resolution of the Israeli-Palestinian conflict.

As a presidential candidate, Mr. Trump vowed to change course. At the annual conference of the American Israel Public Affairs Committee in March 2016, he said he would “move the American embassy to the eternal capital of the Jewish people, Jerusalem.”

But he signed a waiver on June 1, and officials said Mr. Adelson was among the supporters who were deeply disappointed by the president’s decision.

Among those pressing hardest for moving the embassy, said people close to the deliberations, was Vice President Mike Pence, who has been a conduit for Mr. Trump to religious conservatives. In a speech in New York on Tuesday, he said Mr. Trump was “actively considering when and how to move the American embassy in Israel from Tel Aviv to Jerusalem.”

In the short run, the decision could complicate plans for Mr. Kushner and Jason D. Greenblatt, Mr. Trump’s special envoy, to restart peace negotiations. Palestinian officials have warned that Mr. Trump is “playing with fire.”

“If you’re trying to be creative by saying we’re recognizing Jerusalem as Israel’s capital, you’d better qualify it,” said Dennis B. Ross, a longtime Middle East peace negotiator. “If you don’t qualify it, that means you’ve just accepted the Israeli position on the final status of Jerusalem, which means you’ve lost the Arabs.”

A version of this article appears in print on , on Page A6 of the New York edition with the headline: Trump to Keep Embassy in Tel Aviv, but Weigh In on Jerusalem. Order Reprints | Today’s Paper | Subscribe